Okay, this is gonna need a little refining, but here goes:
Strip and put all your clothes in 2 suitcases (all of his clothes in one, all of hers in another) and use a lock or the handcuffs (providing they have keys) to secure them.
Now, the husband gets your key wife, and you get hers husband.
You have 10 minuites to hide the key on (or in) your person. The only rule is that the other person must be able to retreive it (so for example you can't swallow it). Other than that use your imagination to make it as hard as possible to find.
The challenge is to retreive the key to your clothes first. The method of retreival dosn't matter. Establish a safe word to end the game. Otherwise lie cheat and steal
. The loser has to "earn" the key back from the winner, who also has access to all of the losers clothing. However the winner must leave their key where it is. If the loser, at ANY POINT during the dare, retreives their key, the winner will be put in bondage at the mercy of the loser.
I might update this if any refinements come to mind